Extensible fuse extender



June 18, 1968 R. J. KELLY ETAL EXTENSIBLE FUSE EXTENDER 2 Sheets-Sheet 1 Filed Sept. 28, 1965 FIG. 4.

mvewrans RUSSELL J. KELLY CHARLES L. SHIRLEY,JR.

HAROLD ROSEN.

FIG. 1.

ATTORNEY June 18, 1968 R. J; KELLY ETAL EXTENSIBLE FUSE EXTENDER 2 Sheets-Sheet 2 Filed Sept. 28, 1965 I INVENTORS RUSSELL J. KELLY CHARLES L. SHIRLEY,JR.

HAROLD ROSEN IITTORNEY United States Patent 3,388,664 EXTENSIBLE FUSE EXTENDER Russell J. Kelly, Nashua, N.H., Charles L. Shirley, In,

Peabody, Mass, and Harold Rosen, Nashua, N.H., assignors to Sanders Associates, Inc., Nashua, N.H., a corporation of Delaware Filed Sept. 28, 1965, Ser. No. 491,512 Claims. ((31. 1027.4)

ABSTRACT OF THE DISCLOSURE The present invention pertains to free-falling devices and other projectiles, such as aerial bombs, which are to be actuated immediately prior to contact with the earth or some other object, and more particularly to an aerial bomb having an extensible fuse extender assembly including a volute spring. The spring is maintained in its contracted position until a predetermined free fall, whereupon wind pressure activates a release mechanism con nected to said spring to release the same to permit it to extend itself after which it is locked in its extended position by locking means connected thereto. Impact of said extended spring member with the earth or some other object is transmitted to the fuse to cause detonation of the bomb.

This invention relates to free-falling devices such as bombs which require actuation immediately prior to contact with the earth or some other object. The invention has particular application although it is not limited to aerial bomb fuse extenders.

There are various situations encountered by both the military and by industry in which actuation of moving apparatus just prior to contact with the ground or some I object is required. An example in point is that of the freefalling bomb. That is, free-falling bombs often partially or wholly embed prior to detonation. This greatly reduces their effective destruction range. Expensive, sophisticated proximity fuses and permanent fuse extensions have to date been employed to solve this problem. Since storage space is dear and elongation of the bomb greatly complicates handling and deployment, permanent fuse extensions are somewhat less than desirable. State-of-the-art extensible fuse extenders have been of inadequate strength and often collapse without actuating the falling bombs. Furthermore, such prior art extensible fuse extenders are unreliable and are apt to interfere with normal detonation of the bomb on impact.

Accordingly, it is a principal object of this invention to provide new and improved apparatus for actuating freefalling apparatus prior to contact.

It is another object of this invention to provide a new and improved free-falling bomb extensible fuse extender.

It is another object of this invention to provide in combination with a free-falling bomb an extensible fuse extender that is reliable and will not interfere with normal detonation of the bomb.

It is another object of this invention to provide in combination with a free-falling bomb an improved, simplified and inexpensive proximity fuse.

It is another object of this invention to provide in combination with a free-falling bomb an extensible fuse extender that does not appreciably add to the over-all size of the bomb.

It is another object of this invention to provide in combination with a free-falling bomb, an extensible fuse extender having a novel locking device whereby the member when extended has adequate strength to properly detonate the bomb at the moment of contact with the earth or other object.

It is another object of this invention to provide in combination with a free-falling bomb an extensible fuse extender having a novel release mechanism.

It is another object of this invention to provide in combination with a free-falling bomb an extensible fuse ex- ;ender that does not require modification of the existing use.

It is another object of this invention to provide in combination with a free-falling bomb an extensible fuse extender that cannot he accidentally tripped.

These, together with other objects and features of the invention will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which like elements are given like reference numerals throughout and wherein:

FIG. 1 illustrates a bomb in combination with the novel extensible fuse extender of the invention;

FIG. 2 is a sectional view of an extensible fuse extender embodying the principles of the invention;

FIG. 3 is an orthogonal pictorial representation showing the separate elements of one embodiment of the in vention; and

FIG. 4 is a detail illustrating the novel spring locking means of the invention.

Since the invention has particular utility in combination with free-fa1=ling bombs, the following description uses, by way of illustration, such an embodiment. However, since the principles of the invention are equally applicable to the actuating of any movable device prior to contact, it is to be understood that such description is by way of illustration only and that the many applications and embodiments of the invention which will be suggested to those skilled in the art fall within the scope of the invention.

In general, the invention comprehends the use of an extensible volute spring as the fuse extension member, said volute spring being released by means of a release mechanism which, in turn, is activated by the conventional fuse arming mechanism of the bomb. The volute spring, when extended, is locked in place by novel spring locking means.

Referring now to FIG. 1, there is illustrated a bomb 1 in combination with the novel fuse extender apparatus of the present invention. In the illustration of FIG. 1, the fuse extender is in its contracted position and resides within fuse extender housing 5. The various elements of the fuse extender apparatus are illustrated in their relative positions in FIG. 3. Having reference now to FIG. 3, there is illustrated thereby a fuse 2 such as is conventionally used with free-falling bombs. Also illustrated by FIG. 3 as an integral part of fuse 2 is fuse arming mechanism 3. Fuse arming mechanism 3 is actuated by actuating vane 4. That is, as the bomb falls through free space, wind pressure on actuating vane 4 causes it to rotate, thus winding up the fuse arming mechanism. In accordance with the teachings of the present invention, a vane adapter 8 is attached to actuating vane 4. Said vane adapter 8 includes a centrally disposed square aperture suitable to cooperate with the release rod 12 of latch release mechanism 6. Volute extension spring 7 coaxially encompasses latch release mechanism 6 and is normally held in contracted position by a latch, not shown in FIG. 3. When in the contracted position, the volute extension spring 7 and latch release mechanism 6 :are contained within fuse extender housing 5 and nosepiece 9 in the manner illustrated in FIG. 1. Also illustrated in FIG. 3 are locking springs 22 which are affixed to the outside and protrude through apertures in the fuse extender housing.

Operation of the apparatus of the invention, together with a more detailed description of the components, will now be made, having reference to FIG. 2'. FIG. 2 is a ill! sectional view of the apparatus of the present invention and illustrates the volute extension spring in its stored position. Fuse extender housing 5 having aerodynamic vanes 10 is permanently afiixed to the fuse portion of bomb 1 by means of the cut-away portion of fins if). The outer end of volute extension spring 7 is permanently afiixed to the inner portion of the cylindrical portion of fuse extender housing 5. The inner end of volute extension spring 7 is permanently attached to tubular nosepiece extension 16. in the stored position, nosepiece 9 and its tubular extension 16 are inserted within the fuse extender housing 5 as illustrated in FIG. 2 and restrained in this position by means of latch 19 and latch release mechanism 6. The volute extension spring 7 comprises a helically wound fiat ribbon of resilient material formed into a hollow, truncated cone. Such a spring may be fabricated of alloyed steel, stainless steel, beryllium copper or the like. When in a compressed condition, such a spring assumes the configuration of a short cylinder and, due

to its resiliency, exerts a force tending to extend itself to its full length. By way of example, extension spring suitable for application in the present invention are made commercially available by Central Safety Equipment Co. of Philadelphia, Pa, under the trade name of Elasticones. The latch release mechanism comprises the 1' hollow rectangular member containing a threaded release rod 12 which is mounted therein by means of ball bearings 13. Latch release mechanism 6 also includes a lug 21 which, when the apparatus is in its retracted position, restrains latch 19 from moving in a counterclockwise direction about its pivot point .20. Latch release mechanism 6 also includes a release rod follower, which is threaded over threaded release rod 12. Latch release mechanism 6 further includes a slot aperture l8,

which aperture engages release rod follower lug 15. i

Finally, the fuse extender housing 5 includes a restraining notch 11, which notch engages latch 19 to restrain nosepiece 9 and thus volute extension spring 7 in the compressed condition. That is, latch 19 is fixed to tubular nosepiece extension 16 at pivot point 20 and is also engaged in fuse extender housing restraining notch 11. As long as latch 19 is prevented from turning in a counterclockwise direction by latch release lug 21, volute extension spring 7 is unable to extend itself. When the bomb is dropped and is in a free-falling position. actuating vane 4 begins to spin due to wind pressure and performs the function of farming the fuse and operating latch release mechanism 6. As actuating vane 4 rotates, it turns threaded release rod 12 through vane adapter means 8.

As threaded release rod 12 turns, release rod follower 14 moves progressively to the left as release rod follower lug 15 rides along slot aperture 18. A compensating spring 17 prevents any binding of the release rod follower on the threaded release rod. When release rod follower 14 reaches the end of slot aperture 18, continued turning a of threaded release rod 12 begins to cause the entire latch release mechanism housing to move to the left. As the latch release mechanism housing moves to the left. latch release lug 21 is removed from its inhibiting position with respect to latch 19. This allows latch 19 to rotate in a counter-clockwise direction, thus releasing the latch and allowing volute extension spring 7 to extend itself. Timing for the operation of the release mechanism of the invention can of course be readily controlled by means of controlling the length of aperture 18 or by changing the pitch of the threads on threaded release rod 12. As volute extension spring 7 extends itself, nosepiece 9 and the entire latch release mechanism as Well as the volute extension spring 7 itself move outwardly away from the fuse and fuse actuating vane 4. There is thus no possi- 1 bility that a malfunction of the apparatus of the present invention will interfere with the arming of the bomb.

Once the volute extension spring has been fully extended as above described, it is necessary that it be locked in such an extended position. This is so in order that an effective actuating force be transmitted to the fuse at substantially the instant the nosepiece 9 makes contact with earth or some other object. FIG. 4 illustrates a novel latching spring arrangement whereby volute extension spring 7 is locked in place upon extension. This is accomplished by means of bent springs 22 which have one end alfixed to the outer surface of fuse extender housing 5 and the opposite end inserted through apertures E3 into the interior of said fuse extender housing. When volute extension spring 7 releases and extends itself to its full length, the final turn thereof, which is afiixed to the inner surface of the fuse extender housing, automatically contracts due to the nature of devices of this type. As the diameter of such final turn contracts, locking springs 22. due to their bent configuration and resilient forces, slide inwardly into the interior of the fuse extender housing between the last turn of volute extension spring 7 and said housing. They thus restrain this last turn of the volute extension spring in its contracted position. Therefore, since the interior of the last turn of the volute extension spring is small compared to the outer diameter of the penultimate turn thereof, the volute spring cannot be forced back into its retracted cylindrical geometry. There is thus provided an extended member having adequate strength to transmit the impact force on the nosepiece 9 to the fuse 2.

.ihlthough there is shown and described but a single embodiment of the present invention, it will be recognized by persons skilled in the art that changes and modifications are possible within the spirit of the invention and within the scope of the appended claims. Therefore, it is desired that the embodiment shown and described herein shall be considered as illustrative and not as limiting. What is claimed is:

l. A free-falling apparatus to be actuated in response to and prior to contact, comprising said apparatus, actuating means for actuating said apparatus, an extensible member cooperatively engaged with said actuating means, said extensible member being a volute extension spring, said extensible member being stored in a retracted condition. and means for effecting extension thereof during free fall.

12. A free-falling apparatus as defined in claim 1 including means for locking said extensible member in an extended condition subsequent to extension thereof.

.3. A free-falling apparatus as defined in claim 2 wherein said locking means comprises a plurality of locking springs adapted to restrain the largest diameter turn bf said extended volute extension spring in a contracted condition.

4. A free-falling bomb including a fuse adapted to detonate said bomb in response to an impact force, means for arming said fuse, fuse extender means for receiving and communicating to said fuse an impact force prior to physical impact of said bomb, said fuse extender means comprising a volute extension spring, said volute extension spring being restrained in a retracted condition llnlll said bomb is in free fall and released in response to said fuse arming means.

5. A free-falling bomb to be detonated prior to actual physical impact including a fuse,

means for arming said fuse,

a first housing containing an extensible volute spring engaged with said fuse :tnd stored in a retracted condition, means for effecting extension of said volute spring luring free fall, means for locking said volute spring subsequent 11b extension thereof in its extended position, and it second housing, second housing containing it threaded release rod,

.l release rod follower positioned over a portion said 5 6 of said release rod in threaded engagement References Cited therewitla, UNITED STATES PATENTS a longitudinal slot, said release rod follower including an outwardly 1,207,520 12/1916 Fablam 6t 1027'4 extending lug positioned within said slot, where- 5 2,412,695 12/1946 9. et b the length of said slot determined during free 21419349 4/1947 Gnbert 1O2 73 I 22212135 gnrnie for release of said extensible vo ute BENJAMIN A. BORCHELT, Primary Examinermeans connected to said second housing in Ieleaseable G. H. GLANZMAN, Assistant Examinerengagement with said volute spring extension means. 19 

